The majority of automobiles are propelled by internal combustion engines burning fossil fuels. In such vehicles, the internal combustion engine must be running any time that power is required. The engine is typically started while the vehicle is in park using an electric motor provided specifically for that purpose. Until recently, it was common to start the engine at the beginning of a trip and not shut down the engine until reaching the destination. In recent years, hybrid electric vehicles have been introduced to the market. Hybrid electric vehicles are capable of propelling the vehicle using either the internal combustion engine or using a traction motor powered by electrical energy stored in a battery. One way that hybrid vehicles reduce fuel consumption is by shutting the engine off during periods when the motor propels the vehicle or when the vehicle is stopped. When it is necessary or desirable to resume using the internal combustion engine, the engine must be restarted. Often, the engine must be restarted while the vehicle is moving under electric power. Because restart events happen frequently and not necessarily in response to a driver action, the restarts must be smoother than traditional engine starts. Furthermore, some conditions call for a very rapid restart. Although traditional starter motors have adequate durability when used only once per trip, they may not have sufficient reliability if used every time a hybrid electric vehicle needs to start the engine.